Cutting Tool

ABSTRACT

A cutting tool for use in impinging earth strata includes a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, wherein the cutting tool body contains a first socket at the axial forward end thereof. The shank portion generally tapers in the axial rearward direction. The cutting tool also includes a hard cutting member affixed to the cutting tool body within the first socket. The hard cutting member includes an axial forward end and an axial rearward end. The hard cutting member also includes a superhard axial forward portion of the axial forward end thereof, wherein the superhard axial forward portion comprises a substrate and a layer of superhard material adhered to the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/454,661 filed Mar. 21, 2011, which is hereby fully incorporated by reference.

BACKGROUND OF THE INVENTION

The invention pertains generally to a cutting tool that is useful for the impingement of a substrate or earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. More specifically, the invention pertains to the aforementioned cutting tool wherein the cutting tool, which may be either rotatable about its central longitudinal axis or an indexable type cutting tool that is symmetrical about its central longitudinal axis, carries a hard cutting member or a superhard cutting member at the axially forward end thereof. The superhard cutting member can be made from a superhard material (or includes a portion there of made from a superhard material). Superhard materials useful in the present invention include, without limitation, materials such as polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN).

A cutting tool typically presents a generally elongate, cylindrical geometry. The cutting tool comprises an elongate steel cutting tool body, which has an axially forward end and an opposite axially rearward end. A hard cutting member or a superhard cutting member typically affixes to the axial forward end of the cutting tool body. The cutting tool body typically carries an assembly or means by which the cutting tool is rotatable carried by a stationary block or holder on a drum. Alternatively, the cutting tool can be indexable and fixed in place within the block or holder on a drum.

Cutting tools can experience wear in a number of ways due to the environment in which they operate and must be frequently replaced. It would thus be highly desirable to provide an improved cutting tool that experiences an increase in useful tool life as compared to heretofore known cutting tools. It would also be highly desirable to provide an improved cutting tool that may more easily and quickly replaced once it has reached the end of its useful tool life.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a cutting tool body with a central longitudinal axis includes an axial forward end, an axial rearward end, a head portion, a shank portion, and a collar portion. The collar portion is mediate of and contiguous with the head portion and the shank portion. The shank portion has an axial forward end and an axial rearward end and the shank portion has a continuous taper in the axial rearward direction from the axial forward end of the shank portion to the axial rearward end of the shank portion.

In accordance with another aspect of the invention, a cutting tool for use in impinging earth strata includes a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, wherein the cutting tool body contains a first socket at the axial forward end thereof. The shank portion generally tapers in the axial rearward direction. The cutting tool also includes a hard cutting member affixed to the cutting tool body within the first socket.

In accordance with an additional aspect of the invention, a cutting tool for use in impinging earth strata includes a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, wherein the cutting tool body contains a first socket at the axial forward end thereof. The cutting tool also includes a hard cutting member affixed to the cutting tool body within the first socket. A hard cutting member includes an axial forward end and an axial rearward end. The hard cutting member also includes a superhard axial forward portion of the axial forward end thereof, wherein the superhard axial forward portion comprises a substrate and a layer of superhard material adhered to the substrate. The substrate of the superhard axial forward portion generally tapers in the axial rearward direction. The hard cutting member further includes a hard axial rearward portion contiguous with and axially rearward of the superhard axial forward portion and includes a second socket structured and arranged for receiving the superhard axial forward portion. In one aspect of the invention, the layer of superhard material includes polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN).

In accordance with an additional aspect of the invention, a cutting tool for use in impinging earth strata includes a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, wherein the cutting tool body contains a first socket at the axial forward end thereof. The cutting tool also includes a hard cutting member affixed to the cutting tool body within the first socket.

These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side, partially sectional view of a cutting tool, in accordance with an aspect of the invention.

FIG. 2 is an enlarged, partially sectional, exploded view of a hard cutting member of the rotatable cutting tool shown in FIG. 1, in accordance with an aspect of the invention.

DETAILED DESCRIPTION

Referring to the drawings, FIGS. 1-2 illustrate a cutting tool of the invention, generally designated as 10. In one aspect, the invention illustrated herein pertains generally to road planing tools. However, one should appreciate that the invention has application to other kinds of cutting tools useful in other kinds of cutting operations. Exemplary operations include without limitation road planing (or milling), coal mining, concrete cutting, and other kinds of cutting operations wherein a cutting tool with a hard cutting member impinges against a substrate (e.g., earth strata, pavement, asphaltic highway material, concrete, and the like) breaking the substrate into pieces of a variety of sizes including larger-size pieces or chunks and smaller-sized pieces including dust-like particles. In addition, it will be appreciated that the cutting tool 10 of the invention may be manufactured in various sizes and dimensions depending upon the desired application of the tool.

As used herein, the term “cutting tool” generally refers to rotatable cutting tools or indexable cutting tools that are generally fixed in place during use.

Cutting tool 10 has a central longitudinal axis A-A. In one aspect, cutting tool 10 may be symmetrical about and/or rotate about the axis A-A. Cutting tool 10 includes an elongate cutting tool body, generally designated as 12, which typically is made of steel. The shape can be as disclosed in U.S. Pat. No. 7,413,257. Exemplary compositions of the steel for the cutting tool body 12 include without limitation those disclosed in the following document: U.S. Pat. No. 4,886,710 to Greenfield, and U.S. Pat. No. 5,008,073 to Greenfield. The tool assembly is processed to enhance performance as disclosed in U.S. Pat. No. 7,458,646. Elongate cutting tool body 12 presents a generally cylindrical geometry, and has an axial forward end 14 and an axial rearward end 16.

Elongate cutting tool body 12 includes a head portion 18, a shank portion 20 and a collar portion 22 wherein the collar portion 22 is mediate of and contiguous with the head portion 18 and the collar portion 20. The shank portion 20 includes an annular groove 24 adjacent the axial rearward end 16 for receiving a retainer ring 26, as is generally known. In one aspect, when installed into a taper bore tool holder the retainer ring axially may retain the tool and restrict free rotation, i.e. an indexable tool.

The head portion 18 contains a first socket 28 at the axial forward end of the cutting tool body 12. The socket 28 includes a frusto-conical portion 30 and a cylindrical portion 32. The socket 28 further includes a bottom surface 34. One should appreciate that other geometries of a socket may be suitable for use with the cutting tool 10 provided that the geometry of the hard cutting member corresponds to that of the socket. Other geometries that could be used are illustrated, for example, in U.S. Pat. Nos. 4,497,520, 4,981,328 and 5,837,071.

In accordance with an aspect of the invention, the shank portion 20 of the cutting tool body 12 generally tapers in the axial rearward direction. In other words, the shank portion 20 has a diameter D1 at an axial forward end 15 adjacent to or near the collar portion 22 that is larger than a diameter D2 at the axial rearward end 16 of the shank portion 20. In one aspect, the diameter may decrease linearly from the axial forward end of the shank portion 20, i.e., adjacent to or near the collar portion 22, toward the axial rearward end 16. In another aspect, the shank portion 20 has a continuous taper from the axial forward end 15 (i.e. at or near where the shank portion has diameter D1) to the axial rearward end 16 (i.e. at or near where the shank has diameter D2).

In one aspect, the clearance between the tapered shank and the tool block or holder is minimal as compared to standard cutting tool assemblies and, in particular rotatable cutting tools. Known rotatable cutting tools have generally had only cylindrically shaped shanks which have a generous clearance between the shank and tool holder to allow free rotation.

Cutting tool 10 further includes a hard cutting member, generally designated as 40. The hard cutting member 40 may be affixed by, for example, brazing within the first socket 28 at the axial forward end 36 of the cutting tool body 12.

Referring particularly to FIG. 2, the hard cutting member 40 includes an axial forward end 42 and an axial rearward end 44. Hard cutting member 40 further includes a hard axial rearward portion, shown generally by bracket 46. The hard axial rearward portion 46 includes an axial forward face 48 which is contiguous with a concave region 50. The hard axial rearward portion 46 includes a generally frusto-conical portion 52 for cooperating with the frusto-conical portion 30 of the socket 28 and a generally cylindrical portion 54 for cooperating with the cylindrical portion 32 of the socket 28. As stated, the hard axial rearward portion 46 may be affixed to the socket 44 by brazing. Hard axial rearward portion 46 may be made from, for example, a hard material such as, for example, cemented (cobalt) tungsten carbide. Grades of cemented (cobalt) tungsten carbide suitable for use herein include, for example, those disclosed in U.S. Pat. No. 4,859,543 to Greenfield and U.S. Pat. No. 6,197,084 to Smith.

Still referring to FIG. 2, the hard cutting member 40 further includes at the axial forward end thereof a superhard axial forward portion, as shown by bracket 60. The superhard axial forward portion 60 includes a substrate 62 which may be made from, for example, a hard material such as, for example, cemented (cobalt) tungsten carbide. Grades of cemented (cobalt) tungsten carbide suitable for use herein include those disclosed in one or more of the following patent documents, which pertain to a compact of a superhard material and a carbide (or cemented carbide) substrate: U.S. Pat. No. 4,063,909 to Mitchell, U.S. Pat. No. 4,604,106 to Hall et al., U.S. Pat. No. 4,694,918 to Hall, and U.S. Pat. No. 4,811,801 to Salesky et al. One would expect that the grades of cemented carbides disclosed in U.S. Pat. No. 4,859,543 to Greenfield and U.S. Pat. No. 6,197,084 to Smith to also be suitable for use as the substrate. The grade of cemented (cobalt) tungsten carbide suitable for use as substrate 62 may or may not be the same as the grade of cemented (cobalt) tungsten carbide suitable for use as the hard axial rearward portion 46. The specific application for the rotatable cutting tool may dictate the specific grades of cemented (cobalt) tungsten carbide suitable for use therein. In other words, the composition of the substrate 62 may or may not be the same as the composition of the hard axial rearward portion 46.

The superhard axial forward portion 60 further includes a layer of a superhard material 64 adhered to the substrate 62. The layer of superhard material 64 may include, for example, polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN). The layer of superhard material 64 may have a generally constant thickness and can be applied to the substrate 62 by any one of the number of known techniques wherein the superhard material is bonded to the surface of the substrate 62. In addition, the layer of superhard material 64 is shown as having a generally hemispherical shape, but it will be appreciated that it may have other shapes and configurations as desired or needed for particular cutting operations.

One can apply the layer of superhard material 64, e.g. polycrystalline diamond, to the substrate 62 by any one of a number of techniques wherein the layer of superhard material 64 is bonded to the surface of the substrate 62. The following patent documents disclose exemplary compositions of polycrystalline diamond as well as exemplary techniques to apply a layer of polycrystalline diamond to the surface of a substrate: U.S. Pat. No. 4,063,909 to Mitchell, U.S. Pat. No. 4,604,106 to Hall et al., U.S. Pat. No. 4,694,918 to Hall, and U.S. Pat. No. 4,811,801 to Salesky et al.

In accordance with another aspect of the invention, sidewalls 66 of the substrate 62 generally taper in the axial rearward direction. This tapered braze joint shape provides a high strength and better reliability than the simple butt joint geometry typically used by known cutting tools as shown, for example, in U.S. Pat. Nos. 6,051,079 and 7,464,993. The tapered sidewalls 66 of the substrate 62 may be formed by, for example, a grinding process to obtain the generally desired tapered, conical shaped substrate 62.

In another aspect of the invention, the axial forward end 48 of the hard axial rearward portion 46 includes a second socket 56 formed therein. The second socket 56 is structured and arranged for receiving the superhard axial forward portion 60. More particularly, the second socket 56 includes conical sidewalls 68 structured and arranged for receiving the tapered sidewalls 66 of the superhard axial forward portion 60. In one aspect, the sidewalls 68 of the second socket 56 generally taper in the axial rearward direction similar to the tapering of the sidewalls 66 of the substrate 62.

In another aspect of the invention, the sidewalls 68 of the second socket 56 may be formed at an angle X1, which in one exemplary embodiment may be about 30°. The angle X1 may range from about 10° to about 60°. These are all angles that can be economically pressed and sintered with conventional carbide processing technology. Similarly, the sidewalls 66 of the substrate 62 may be formed at an angle X2, which in one exemplary embodiment may be about 30° for corresponding to the tapered sidewalls 68 of the second socket 56. In one aspect, the angle X2 may be in the range of about 1° to about 2° larger than the angle X1.

As described, the superhard axial forward portion 60 is received in the second socket 56 of the hard axial rearward portion 46. In particular, the superhard axial forward portion 60 is affixed to the hard axial rearward portion 46 by brazing the sidewalls 66 of the substrate 62 to the sidewalls 68 of the second socket 56. Although not required, brazing may also be provided between a bottom surface 70 of the substrate 62 and a bottom area 72 of the second socket 56. The tapered insert brazing geometry provides more surface area to bond the superhard axial forward portion 60 to the hard axial rearward portion 46 allowing smaller diameter cutting inserts to be used as compared to the known butt brazed cutting inserts for cutting tools. In one aspect, smaller cutting insert diameters will enable higher machine speeds. It will be appreciated that other methods of attachment besides brazing, e.g. gluing and other attachment methods known in the art, may be used with the invention.

Whereas particular aspects of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims. For example, in one aspect the tapered shank aspect, e.g. shank 20, may be used with various types of cutting tools having various types of cutting inserts, e.g. superhard cutting inserts (e.g., PCD or PCBN) or hard cutting inserts (e.g, carbide cutting inserts) and the like. Shanks that are not tapered can also be used in association with aspect of the invention. In another aspect, various types of cutting inserts having various shapes and configurations may be used wherein the sidewalls of the insert are brazed to the sidewalls of the socket in which it is received. In addition, the axial forward end of the cutting insert can have various shapes and configurations such as, for example, hemispherical, frusto-conical, conical or other known shapes for cutting inserts as desired. In another aspect, either superhard cutting inserts (e.g., PCD or PCBN) or hard cutting inserts (e.g, carbide cutting inserts) or combinations thereof may be used with the invention. 

1. A cutting tool body with a central longitudinal axis, the cutting tool body comprising: an axial forward end and an axial rearward end; a head portion, a shank portion and a collar portion, and the collar portion being mediate of and contiguous with the head portion and the shank portion; wherein the shank portion has an axial forward end and an axial rearward end and the shank portion has a continuous taper in the axial rearward direction from the axial forward end of the shank portion to the axial rearward end of the shank portion.
 2. The cutting tool body of claim 1, wherein a diameter of the shank portion adjacent the axial forward end of the shank portion is larger than a diameter of the shank portion adjacent the axial rearward end.
 3. The cutting tool body of claim 1, wherein a diameter of the shank portion decreases linearly from adjacent the axial forward end to the axial rearward end.
 4. A cutting tool for use in impinging earth strata, the cutting tool comprising: a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, the cutting tool body containing a first socket at the axial forward end thereof; wherein the shank portion generally tapers in the axial rearward direction; and a hard cutting member being affixed to the cutting tool body within the first socket, the hard cutting member comprising: an axial forward end and an axial rearward end; a superhard axial forward portion at the axial forward end thereof; and a hard axial rearward portion contiguous with and axially rearward of the superhard axial forward portion and having a second socket for receiving the superhard axial forward portion.
 5. The cutting tool of claim 4, wherein the superhard axial forward portion comprises a substrate and a layer of a superhard material adhered to the substrate.
 6. The cutting tool of claim 5, wherein the layer of superhard material includes polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PcBN).
 7. The cutting tool of claim 5, wherein the substrate of the superhard axial forward portion generally tapers in the axial rearward direction.
 8. The cutting tool of claim 7, wherein the second socket includes sidewalls structured and arranged for receiving the tapered substrate of the superhard axial forward portion.
 9. The cutting tool of claim 8, wherein the sidewalls of the second socket generally tapers in the axial rearward direction.
 10. The cutting tool of claim 8, wherein the tapered substrate is brazed to the tapered sidewalls of the second socket.
 11. The cutting tool of claim 4, wherein the hard axial rearward portion includes a cemented (cobalt) tungsten carbide material.
 12. The cutting tool of claim 5, wherein the substrate of the superhard axial forward portion includes a cemented (cobalt) tungsten carbide material.
 13. A cutting tool for use in impinging earth strata, the cutting tool comprising: a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, the cutting tool body containing a first socket at the axial forward end thereof; and a hard cutting member being affixed to the cutting tool body within the first socket, the hard cutting member comprising: an axial forward end and an axial rearward end; a superhard axial forward portion at the axial forward end thereof, wherein the superhard axial forward portion comprises a substrate and a layer of a superhard material adhered to the substrate, and wherein the substrate of the superhard axial forward portion generally tapers in the axial rearward direction; and a hard axial rearward portion contiguous with and axially rearward of the superhard axial forward portion and having a second socket structured and arranged for receiving the superhard axial forward portion.
 14. The cutting tool of claim 13, wherein the layer of superhard material includes polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PcBN).
 15. The cutting tool of claim 13, wherein the second socket includes sidewalls structured and arranged for receiving the tapered substrate of the superhard axial forward portion.
 16. The cutting tool of claim 15, wherein the sidewalls of the second socket generally taper in the axial rearward direction.
 17. The cutting tool of claim 16, wherein the tapered substrate is brazed to the tapered sidewalls of the second socket.
 18. The cutting tool of claim 13, wherein the shank portion generally tapers in the axial rearward direction.
 19. The cutting tool of claim 13, wherein the hard axial rearward portion includes a cemented (cobalt) tungsten carbide material.
 20. The cutting tool of claim 13, wherein the substrate of the superhard axial forward portion includes a cemented (cobalt) tungsten carbide material.
 21. The cutting tool body of claim 1, wherein the cutting tool body is either rotatable or indexable.
 22. The cutting tool of claim 4, wherein the cutting tool body is either rotatable or indexable.
 23. The cutting tool of claim 13, wherein the cutting tool body is either rotatable or indexable.
 24. A cutting tool for use in impinging earth strata, the cutting tool comprising: a cutting tool body having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, the cutting tool body containing a first socket at the axial forward end thereof; wherein the shank portion generally tapers in the axial rearward direction; and a hard cutting member being affixed to the cutting tool body within the first socket. 